Can you flower with 14 hours of light?
Consequently, it requires a night cycle long enough to induce flowering. The critical night length, or the amount of time required for the photoperiod response in Cannabis to occur in order to stimulate flowering, is between nine and 10 hours, which corresponds to 14 to 15 hours of daylight, but it varies by cultivar.
You'll need around 14 hours of light to make sure a lot of your plants' PFR doesn't convert to PR. Less than that and your plant may start flowering earlier than expected, but any more light than that won't harm the plant.
For your plants to move from their vegetative stage to the flowering stage, they will need to be exposed to 12 or more hours of darkness each day to start flowering.
Light Cycle for Indoor Flowering Period
When growing indoors, growers will typically put plants on a schedule of 12 hours of light and 12 hours of darkness (12/12) once plants have reached the desired size during the vegetative period.
Using the Wrong Light Schedule
Cannabis needs about 18-24 hours of light during the vegetative stage and 12 hours of light during the flowering stage.
The 6/2 light schedule means that the plants can process more light and get adequate rest at the same time. Thus, this approach puts minimal stress on the plants, and it's the best light cycle for flowering.
Every strain is a bit different. Cannabis starts budding when plants get at least 12 hours of uninterrupted darkness each night.
As plants grow taller, the bigger leaves on top shade the lower leaves and branches. That can lead to small plants with buds on only the highest tier. By gently bending the top of a plant, you bring light to the lower leaves, increasing the colas (nodes where buds form) and bringing light to lower-level buds.
Height of plant: Depending on the strain, plants will generally double in size during flowering. So, if 'room' height is limited, the switch to 12/12 will need to be done no later than when the plant has reached 50% of the 'available' height (remember to consider the minimum gap distance between lamp and foliage).
When you grow indoors, flowering will begin once you switch your lights to 10-12 hours of darkness. For most cannabis strains, the flowering period will last about 7-9 weeks, although some sativas require even longer for their buds to mature.
Should I increasing light during flowering?
Once the light cycle is changed to 12 hours, adding more light to the plants helps increase the flowers and yield.
Cannabis plants need short days (or more specifically long nights) in order to start flowering and make buds. Most indoor growers give their plants 12 hours of darkness and 12 hours of light each day to initiate budding and continue with that 12/12 light schedule until it's time to harvest.
Myth #14: LED Lights Can't Damage Plants
The reality is that modern LED grow lights can produce a very high level of light and it can cause photo-bleaching and burn leaves. This depends very much on the plant, but a PPFD of 800 is enough to damage some plants.
Plants exhibit several signs when they're getting too much light. The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.
Lower wattage LEDs of around 200 watts should sit between 12-20 inches from the top of the plant. Higher wattage LEDs of 1000 watts and above should sit between 36-46 inches from the top of the plant.
Stress is the number one cause of popcorn buds.
Any kind of stress, be it from poor watering, a lack or excess of nutrients, the environment, pests, plagues, or improper care, can affect a plant's ability to grow big, dense flowers.
Most houseplants do well with 12-16 hours of artificial fluorescent light each day. Too little light will result in elongated, spindly growth and too much light will cause a plant to wilt, color to fade, soil to become excessively dry and foliage to burn. Plants also require a rest period each day.
For most types of plants, 12 to 18 hours of light per day is sufficient to allow proper growth, and even flowering, as well as setting fruit. However if your plants get some sunlight–from a window, for example–you could turn off the grow light while the plants receive natural sunlight.
Plants have evolved their own sun protection, called photoprotection, which leaves turn on in full-sun and turn off when shaded by a cloud or another leaf. Without this process, full sunlight would cause oxidation and bleach the leaves—the plant equivalent to a severe sunburn.
When full sun is the only light level listed for a plant, that means it is going to need at least six hours of direct sunlight to grow and bloom. If you plant it in a lesser amount of light, it likely will not bloom and in some cases the plant may not survive.
